1. Field of the Invention
The present invention relates to a media transport belt. More specifically, the present invention relates to a belt that is used for transporting single sheets of paper, overhead transparency film, or the like in an electrophotographic apparatus such as a copying machine, a laser beam printer, and a facsimile, or a belt that is used for transporting or drying shingle sheets of paper, overhead transparency film, or the like in an ink jet printer or bubble jet printer.
2. Description of Related Art
Electrophotographic apparatuses such as a copying machine employs a method for transporting a sheet of paper, film and the like by mounting it on a resin belt made of PC, vinylidene fluoride, or the like, or by attracting it to the surface of a resin belt which is electrically charged previously.
In the case of transporting single sheets of paper, film or the like by a resin belt, stable conveyance is difficult to be achieved because paper or the like often slips on the belt. When single sheets of paper, film or the like are transported by attracting them by electric charges provided to the belt, paper cannot be accurately attracted on the belt due to lack of attraction force for a sheet, which causes a problem that the tip portion of a sheet is warped upward during transportation. Especially, in order to obtain a higher-speed printer, it is necessary to improve attraction force of the belt for a sheet as well as to attract such media as paper or overhead transparency film more accurately to the belt. Moreover, it is necessary that the belt has adequate attraction force for a sheet under various conditions, for example, under high temperature and high humidity conditions.
In the case of an ink jet printer or bubble jet printer, it is necessary to dry ink during transportation of a sheet. For this reason, the belt is required to have heat resistance. Furthermore, in order to shorten the drying time by drying the belt at a higher temperature, the belt is required to have much higher heat resistance. The belt is also required to have ink resistance to prevent deterioration of the belt caused by the component of ink and to prevent dielectric breakdown caused by water absorption of a sheet. Moreover, the belt is required to be prevented from being deteriorated due to the ink adhering to the surface of the belt. In many cases, ink for a printer is alkaline, therefore, the belt is required to have resistance to alkali.
As the result of our researches to solve the above problems and to obtain a high-speed printer or the like, the inventors of the present invention have eventually attained a media transport belt which has excellent heat resistance, high withstanding voltage, and ink resistance in response to its structure and material properties, and to which a sheet is electrostatically attracted through the application of voltage to the electrodes formed on it.
A media transport belt according to the present invention, which overcomes the above-discussed and numerous other disadvantages and deficiencies of the prior art, comprising: a tubular film made of polymeric material; conductive electrodes formed in predetermined patterns on the outer surface of the tubular film; and an electrode protective layer formed on the electrodes, wherein the electrode protective layer consists of resin or composite resin having volume resistivity of 109xcx9c1015 xcexa9xc2x7cm and dielectric constant of equal to or greater than 3.0.
Polymeric material for a tubular film is not particularly limited, but such material having a proper tensile elastic modulus and a proper glass transition temperature can be selectively used as polymeric material for the tubular film.
As resin or composite resin for an electrode protective layer, such resin or the like having a low coefficient of water absorption or having ink resistance can be selectively used.
Accordingly, an object of the present invention is to provide a media transport belt having an excellent electrostatic attraction force and being capable of transporting single sheets of paper or overhead transparency film by attracting them adequately to its surface.
Another object of the present invention is to provide a media transport belt having an excellent electrostatic absorption under high temperature and high humidity conditions and an excellent resistance to dielectric breakdown caused by water absorption by forming an electrode protective layer from resin with low coefficient of water absorption.
A further object of the present invention is to provide a media transport belt having a sufficient attraction force for printed media, an excellent electrostatic attraction force under high temperature and high humidity conditions, an excellent resistance to dielectric breakdown caused by water absorption, and excellent ink resistance, even if it is used in an ink jet printer. The above force and resistances are provided to the belt by forming an electrode protective layer of the belt from resin having low coefficient of water absorption, and by providing an ink-resistant outer layer to the outer surface of the electrode protective layer of the belt.